Abstract:
:Many papers discussed the I value for water given by the ICRU, concluding that a value of about 80 +/- 2 eV instead of 67.2 eV would reproduce measured ion depth-dose curves. A change in the I value for water would have an effect on the stopping power and, hence, on the water-to-air stopping power ratio, which is important in clinical dosimetry of proton and ion beams. For energies ranging from 50 to 330 MeV/u and for one spread out Bragg peak, the authors compare the impact of the I value on the water-to-air stopping power ratio. The authors calculate ratios from different ICRU stopping power tables and ICRU reports. The stopping power ratio is calculated via track-length dose calculation with SHIELD-HIT07. In the calculations, the stopping power ratio is reduced to a value of 1.119 in the plateau region as compared to the cited value of 1.13 in IAEA TRS-398. At low energies the stopping power ratio increases by up to 6% in the last few tenths of a mm toward the Bragg peak. For a spread out Bragg peak of 13.5 mm width at 130 mm depth, the stopping power ratio increases by about 1% toward the distal end.
journal_name
Med Physjournal_title
Medical physicsauthors
Henkner K,Bassler N,Sobolevsky N,Jäkel Odoi
10.1118/1.3085877subject
Has Abstractpub_date
2009-04-01 00:00:00pages
1230-5issue
4eissn
0094-2405issn
2473-4209journal_volume
36pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE/OBJECTIVE:Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12104
更新日期:2017-03-01 00:00:00
abstract:PURPOSE:A modular phantom for dosimetry and imaging performance evaluation in cone-beam computed tomography (CBCT) is reported, providing a tool for quantitative technical assessment that can be adapted to a broad variety of CBCT imaging configurations and clinical applications. METHODS:The phantom presents a set of m...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13952
更新日期:2020-02-01 00:00:00
abstract::An in vitro radiographic technique which uses saline/iodine displacement has been developed to study the thickness of bone-equivalent and soft-tissue-equivalent materials within atherosclerotic plaques in arterial specimens which have been cut open longitudinally and laid flat. Results concerning the optimization of t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597916
更新日期:1997-01-01 00:00:00
abstract::In intensity modulated radiation treatments (IMRT), the position of the field edges and the modulation within the beam are often achieved with a multileaf collimator (MLC). During the MLC calibration process, due to the finite accuracy of leaf position measurements, a systematic error may be introduced to leaf positio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2335490
更新日期:2006-09-01 00:00:00
abstract::The mixed-field dosimetry for 252Cf Applicator Tube (AT) type medical sources available from Oak Ridge National Laboratory (ORNL) has been characterized using ionization chambers, a GM counter, and Monte Carlo methods. Unlike the AAPM Task Group No. 43 (TG-43), specification of dose to muscle instead of water is recom...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598646
更新日期:1999-08-01 00:00:00
abstract::The image display is an important component of the Picture Archiving and Communication System (PACS) and of digital imaging in general. In this paper, we assess the display performance of 32 different flat panel LCD devices, in terms of their reflection, luminance response, luminance uniformity, resolution, noise, vei...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1764946
更新日期:2004-07-01 00:00:00
abstract::A method for finding optimal primary fluence profiles for multiple field external beam radiation therapy techniques has been developed using a radiobiologically based objective function that quantifies the probability of achieving complication-free tumor control, P+. The objective function P+ has the valuable property...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596971
更新日期:1993-07-01 00:00:00
abstract:PURPOSE:To develop a probabilistic treatment planning (PTP) method which is robust to systematic patient setup errors and to compare PTP plans with plans generated using a planning target volume (PTV) margin optimized to give the same target coverage probability as the PTP plan. METHODS:Plans adhering to the RTOG-0126...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3679856
更新日期:2012-02-01 00:00:00
abstract:PURPOSE:To experimentally commission a dual-energy CT (DECT) joint statistical image reconstruction (JSIR) method, which is built on a linear basis vector model (BVM) of material characterization, for proton stopping power ratio (SPR) estimation. METHODS:The JSIR-BVM method builds on the relationship between the energ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13287
更新日期:2019-01-01 00:00:00
abstract::An x-ray computed microtomography system for specimen and small animal imaging was built and tested. The system used seventeen 48-microm-wide detector arrays (a charge coupled device camera) and helical acquisition techniques. Images were acquired using 540 rays/view and 400 views/2pi. The modulation transfer function...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598662
更新日期:1999-08-01 00:00:00
abstract:PURPOSE:Carpal tunnel syndrome (CTS) is the common entrapment neuropathy that occurs due to compression of the median nerve at the wrist. Ultrasound images have been used to highlight anatomical variants of the median nerve, and CTS is thought to be associated to enlargement of the cross-sectional area (CSA) of the med...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4767754
更新日期:2012-12-01 00:00:00
abstract:PURPOSE:Partial scan reconstruction (PSR) artifacts are present in myocardial perfusion imaging using dynamic multidetector computed tomography (MDCT). PSR artifacts appear as temporal CT number variations due to inconsistencies in the angular data range used to reconstruct images and compromise the quantitative value ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3665767
更新日期:2012-01-01 00:00:00
abstract::It is known that motion of an object imaged by magnetic resonance imaging leads to errors and artifacts in the image. This effect is especially important when a pulse sequence with long echo time (TE) and long TR is used to provide T2-weighted images. We have modified the usual spin warp imaging pulse sequence in a wa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596026
更新日期:1987-07-01 00:00:00
abstract::Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programm...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598940
更新日期:2000-04-01 00:00:00
abstract::Calibrated C-arm fluoroscopy is used for a variety of surgical procedures where surgical tools and anatomical structures need to be located in space. Calibration can be performed online by combining measurements of the geometry of the image (center and radius) with measurements of a grid of fiducial markers. This arti...
journal_title:Medical physics
pub_type: 杂志文章,多中心研究
doi:10.1118/1.1781331
更新日期:2004-09-01 00:00:00
abstract::To develop volumetric micro-CT fluoroscopy for small animal imaging, we have proposed a cone-beam system with multiple x-ray sources. In this paper, we extend Parker's single-source half-scan weighting scheme to the case of an odd number of x-ray sources that are equiangularly distributed, and apply it for half-scan F...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1381549
更新日期:2001-07-01 00:00:00
abstract:PURPOSE:When an intensity-modulated radiation beam is delivered to a moving target, the interplay effect between dynamic beam delivery and the target motion due to miss-synchronization can cause unpredictable dose delivery. The portal dose image in electronic portal imaging device (EPID) represents radiation attenuated...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4799941
更新日期:2013-05-01 00:00:00
abstract::Dose to the total body from induced radiation resulting from primary exposure to radiotherapeutic beams is not detailed in routine treatment planning though this information is potentially important for better estimates of health risks including secondary cancers. This information can also allow better management of p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1612947
更新日期:2003-10-01 00:00:00
abstract::Recent working groups of the AAPM [Almond et al., Med. Phys. 26, 1847 (1999)] and the IAEA (Andreo et al., Draft V.7 of "An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water," IAEA, 2000) have described guidelines to base reference dosimetry of high energy photon beams on absorb...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1328081
更新日期:2000-12-01 00:00:00
abstract:PURPOSE:In photon radiotherapy, respiratory-induced target motion can be accounted for by internal target volumes (ITV) or mid-ventilation target volumes (midV) defined on the basis of four-dimensional computed tomography (4D-CT). Intrinsic limitations of these approaches can result in target volumes that are not repre...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14023
更新日期:2020-04-01 00:00:00
abstract::The concept of equivalent uniform dose (EUD) has been suggested as a means to quantitatively consider heterogeneous dose distributions within targets. Tumor cell density/function is typically assumed to be uniform. We herein propose to use 18F-labeled 2-deoxyglucose (FDG) positron emission tomography (PET) tumor imagi...
journal_title:Medical physics
pub_type: 临床试验,杂志文章
doi:10.1118/1.1779372
更新日期:2004-09-01 00:00:00
abstract:PURPOSE:Precise segmentation of clinical target volume (CTV) is the key to stomach cancer radiotherapy. We proposed a novel stochastic width - deep neural network (SW-DNN) for better automatically contouring stomach CTV METHODS: SW-DNN was an end-to-end approach, of which the core component was a novel SW mechanism tha...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14733
更新日期:2021-01-27 00:00:00
abstract:PURPOSE:The feasibility of intensity modulated brachytherapy (IMBT) to improve dose conformity for irregularly shaped targets has been previously investigated by researchers by means of using partially shielded sources. However, partial shielding does not fully explore the potential of IMBT. The goal of this study is t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3456598
更新日期:2010-07-01 00:00:00
abstract:PURPOSE:The measurement of malignant pleural mesothelioma is critical to the assessment of tumor response to therapy. Current response assessment standards utilize summed linear measurements acquired on three computed tomography (CT) sections. The purpose of this study was to evaluate manual area measurements as an alt...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4810940
更新日期:2013-08-01 00:00:00
abstract::Transmission data for 4-MV bremsstrahlung beams have been measured with a combination of lead and aluminum attenuators. From these data, the original energy spectra have been reconstructed using an iterative least-squares technique, previously evaluated by simulation studies. The spectra on the central axis for three ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595356
更新日期:1983-11-01 00:00:00
abstract::The relative sensitivity of the half-value layer (HVL) method as a quality index for megavoltage x-ray beams is examined by theoretical calculation and experimental measurements for 4-, 6-, 10-, and 25-MV x-ray beams. It is shown that lower atomic number materials are more sensitive to beam quality changes than higher...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595794
更新日期:1985-01-01 00:00:00
abstract::Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597412
更新日期:1994-10-01 00:00:00
abstract:PURPOSE:In CT-guided liver tumor ablation interventions, registration of a preoperative contrast-enhanced CT image to the intraoperative CT image is hypothesized to improve guidance. This is a highly challenging registration task due to differences in patient poses and large deformations, and therefore high registratio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12332
更新日期:2017-07-01 00:00:00
abstract::The trend toward conformal techniques in stereotactic radiosurgery necessitates an accurate and practical method for verification of irregular three-dimensional dose distributions. This work presents the design and evaluation of a phantom system facilitating the measurement of conformal dose distributions using one or...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598962
更新日期:2000-05-01 00:00:00
abstract::Deformable image registration is an important tool for image-guided radiotherapy. Physics-model-based deformable image registration using finite element analysis is one of the methods currently being investigated. The calculation accuracy of finite element analysis is dependent on given boundary conditions, which are ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1774131
更新日期:2004-09-01 00:00:00